Along with the recent inclination toward multifunction, miniaturized and light-weight electronics, patterns of wiring circuit have been highly integrated, and multiple pins and narrow-pitched fine patterns have been employed in the field of semiconductors. In view of the fine patterns of circuits, anisotropic conductive films have been used to connect plural conductor patterns formed on a substrate with patterns of a conductor to be connected therewith or with IC or LSI. An anisotropic conductive film is a film which shows electrical conductivity in a certain direction alone, and is electrically insulated in other directions.
An anisotropic conductive film can be produced by dispersing conductive fine particles in an adhesive film, or forming through-holes in an adhesive film and filling the holes with a metal by plating.
The anisotropic conductive film can be made by the former method at low costs, but has a shortcoming in that it has poor reliability of a narrow-pitched electrical connection, due to the addition of conductive fine particles to the adhesive film.
In contrast, the latter method provides high reliability of a narrow-pitched electrical connection by forming through-holes with high precision, but is costly due to the complicated and time-consuming steps of perforation and filling of the metal.